We duo queued as DPS, we're pretty well geared for non-legacy (average item level over 60), and Titan could hold threat off of us as going all out as long as we gave him 5 seconds to pick up. He was able to tank all three bosses and trash.
Particularly, I could AoE trash without him losing threat. I cannot do this with any tank, no matter how geared.

Why is this? Do tanks just lack strong AoE threat tools?